Spectrophotofluorometric Determination of 6-Methoxy-2-benzoxazolinone, an Indicator of Resistance to European Corn Borer in Zea Mays12

Abstract

By isotopic dilution Klun and Brindley (J. Econ. Entomol. 59: 711-8) showed the yield of 6-methoxy-2-benzoxazolinone (6MBOA) from maize at the whorl stage to be a reliable indicator of the plant’s resistance to the first-brood larvae of the European corn borer, Ostrinia nubilalis (Hübner). A spectrophotofluorometric method was devised to facilitate analysis of 6MBOA produced from the plant. Excitation of the compound at 292 mµ produced peak emission at 335 mµ the relative in tensity of the emission linear with concentrations of compound between 0.025 to 1.2 µg per ml. When 9 samples of maize, found to contain 234-1810 ppm of 6MBOA by isotopic dilution, were analyzed by the fluorometric procedure, results were in good agreement. Maize extracts contain a small amount of benzoxazolinone (BOA), which does not interfere with the 6MBOA analysis. 6MBOA and BOA in the µg range may be gas chromatographed, but the responses were not reliable for quantitative analysis.